The present invention relates to a stretching device, particularly useful for the relieving or preventing of lower back pains.
It is well known that lower back pains affect a very large proportion of adults, especially middle aged adults and older. As a consequence, a great deal of suffering and disability is experienced by a large fraction of the population resulting, among other things, in a large number of lost work days and greatly diminished quality of life.
A brief physiological analysis will help illustrate the cause of back pains and give an insight as to possible remedies.
The spinal column consists of thirty three vertebrae which are joined together by cartilage tissue and ligaments. The upper twenty four vertebrae are discrete and movable while the lower nine vertebrae are fixed. Five of the lower nine vertebrae are fused together to form the sacrum while the terminal four vertebrae are normally fused to form the coccyx. The normal spinal column may be considered to have seven cervical, twelve thoracic, five lumbar, five sacral and four coccygeal vertebrae. Mobility of the vertebrae in the cervical, thoracic and lumbar regions is relatively free compared with movement of the fused vertebrae of the sacrum and coccyx which is relatively constrained.
The main causes of common back pain are the continual stresses and strains experience by the lower back region which is the major, albeit not the sole, weight supporting element of the upper body.
These stresses and strains eventually cause the damage symptomatic of back pain in that the cartilage material forming the discs separating the vertebrae is worn away over a period of time. In its extreme pathological condition, the patient may develop anchilosing spondylitis, namely, the partial, bent-down stiffening of the spinal column.
The sensation of pain is felt because the distance separating the vertebrae becomes narrower, causing pressure to be exerted on the nerve roots which extend from the spinal cord.
Due to the degenerative nature of the causes of back pain of this sort there is currently no permanent relief available, except for surgery where appropriate. There are, however, a multitude of known procedures for the relief of pain in the lumbar region of the back. These procedures involve the stretching of the lower back to achieve the separation of the discs in the affected lumbar area. However, these treatments typically require the use of weights and other mechanical equipment and must be undertaken only under close professional supervision.
U.S. Pat. No. 5,772,612 to Daniel Ilan, hereby incorporated by reference, proposes a device suitable for home use in which a user lies on an underlying surface with his or her knees over a frame and feet against a foot rest. The lower end of the device contacts the underlying surface, acting as a fulcrum. When the user pushes against the device, the device pivots so as to tend to lift the user""s legs along a slightly arched path. A motor-driven version of the device is also proposed.
The device of the aforementioned patent represents a useful attempt to provide a device for relieving lower-back pain suitable for home use. It has been noted, however, that the resulting motion, namely, a slightly arched reciprocating motion, differs considerably from the sequence of motion performed by a trained physiotherapist. Specifically, with reference to FIGS. 1A-1C, a trained physiotherapist typically performs an initial lifting movement by raising the subject""s legs from the position of FIG. 1A to that of FIG. 1B so as to neutralize the arched concavity of the back. This is followed by a primarily horizontal pulling motion (FIG. 1C), thereby applying tension tending to relieve pressure between the lumber vertebrae. The tension is then released, thereby allowing the body to return under the action of gravity to a resting position.
There is therefore a need for a device for preventing or relieving pain in the lower back of a human subject which would more closely emulate the aforementioned therapeutic movement used by trained physiotherapists.
The present invention is a device for preventing or relieving pain in the lower back of a human subject.
According to one aspect of the present invention, there is provided a device for preventing or relieving pain in the lower back of a human subject for use while the subject lies in a supine position on an underlying surface, the device comprising: (a) a body-engaging element configured for engaging the two legs of the subject inferior to the subject""s lumbar vertebrae; and (b) a drive mechanism mechanically linked to the body-engaging element, the drive mechanism being configured to move the body-engaging element through a repetitive cyclic motion including: (i) an operative motion along a first path operative to move both legs of the subject engaged by the body-engaging element together through the first path such as to apply tension to the lower back of the subject, and (ii) a return motion along a second path, the second path being different from, and lying generally below, the first path.
According to a further feature of the present invention, the body-engaging element includes a surface configured for engaging a rear surface of both knees of the subject.
According to a further feature of the present invention, the first path includes a primarily vertical lifting motion followed by a primarily horizontal tensioning motion.
According to a further feature of the present invention, the second path includes a primarily vertical lowering motion followed by a primarily horizontal return motion.
According to a further feature of the present invention, the first and second paths together form a closed curve lying substantially in a vertical plane. The closed curve preferably approximates to the form of an ellipse.
According to a further feature of the present invention, the drive mechanism includes at least one rotating element, the repetitive cyclic motion being generated at least in part by an off-axis linkage, i.e., a link coupled to the rotating element and eccentric to the rotary axis of the rotating element.
According to another aspect of the present invention, there is provided a device for preventing or relieving pain in the lower back of a human subject, the device being configured for use while the subject lies in a supine position on an underlying surface, the device comprising: (a) a body-engaging element configured for engaging a body part of the subject inferior to the subject""s hip joint joining the thigh to the hip; and (b) a rotary drive for driving the body engaging element, the rotary drive including a pivot pin pivotally mounting the body engaging element and slidable within a slot during the rotation of the rotary drive such as to drive the body-engaging element, and the body part when engaged thereby, from an initial position through repetitive closed-loop cycles each including: (i) a forward stroke path having a vertical lifting component for lifting the engaged body part such as to neutralize the natural arched concavity of the subject""s back, and a horizontal pulling component for tensioning the engaged body part, and the subject""s thigh, such as to relieve pressure in the subject""s lumber vertebrae; and (ii) a return stroke path, different from and underlying, the forward stroke path, for returning the engaged body part to its initial position.